A server system includes system boards each of which is mounted with processors, a cross bar, IOCs (Input/Output component or input/output devices), and node controllers, for example. In the above server system, bit length of destination IDs used by the IOCs and so on is fixed. Therefore, there is a limit in the number of destination IDs. This is because, when the server system is installed, the number of bits of destination IDs is not necessarily secured assuming a large system.
When the number of bits of destination IDs is “3”, the IOCs and so on can issue messages to only “8” kinds of destinations. When the number of connection destinations is “8” or less, the IOCs and so on can transmit messages to other all IOCs and so on.
However, there is a case, that the number of connection destinations increases from “8” or less when the server system is installed, but the number increases to nine or more, since necessity for expansion of nodes occurs after the installment. In this case, a message cannot be issued to IOCs and so on, to which destination IDs are not assigned in the server system, from the other IOCs and so on. Therefore, a user needs to change the overall structure of the server system.
A communication control apparatus between processors is known which can easily perform, within a specified number of ports, change and increase of housing positions for a processor and an input/output device housed in the apparatus.
Patent Document 1: Japanese Laid-Open Patent Publication No. 2000-132527